CA1131903A - Method and apparatus for drying products with a closed gas stream and a desiccant liquid - Google Patents

Abstract

ABSTRACT

Method and apparatus for drying products with a closed gas stream and a desiccant liquid A method of and apparatus for drying products with a gas stream passing the product to extract moisture therefrom and a contacting device producing at least one desiccant liquid layer in the vicinity of the product to be dried, which liquid layer removes moisture from the gas. The gas stream is bubbled through a substantially horizontal liquid layer or can pass between liquid film conducting elements. The desiccant liquid is continuously regenerated. By means of several partial gas streams and a contacting device having more separated liquid film modules, a counter-current type of drying is possible. The product to be dried can be heated to a predetermined temperature by the desiccant liquid through the drying gas stream.

Description

~3~3 ~ethO6L and ~pp~abu~ ~or d:r~g~n~ produGt~ ~i'ch a olo~ed g~s ~re~m ~nd ~ ~e3i~an~ llquld ~Ipplio~ Ener~l~g~z~lkod~:i Tnt~e~ ~ ~u~pe~ g~
In~entoral~ I)r, I,~zl~ 8~5l8 meshanie11 engi~e~
Ahdr~ Ho~r~bh meoh~nl~ e~Bl~ee~ 4 %
Em~ ~8IGMO.~l) me~hani~e~l eIl~i~0er 4 ~.
G;s~orgy lW~ meoh~1~ ng~ee~ 2 a~l o~ Budaps~, Hung~ry ~hl~ n~o~ r~ o ~ m~lih d~r~:ne pro~u~ 0~ d ~
~o~anb ~~ ~ u~ m~nla~l~g ~h~ ~L~ r~ 3~ 3 ~h~ 31~ m, W~ll~lOW~ ~hod fox~ d~ uo ~he ~ a~ ~ b0 ~d 1~ bro~ Yl~ 'v ~ b ~t ~O~ kl ' '., . .,~, :
..
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~3~6)3

2 --~th some ga~,, ln mo~ e~ with alr Im~aburabe~ with mol~ture~ this ~y bhe materi~1 æe~ arlar5, the ga~ more ~nd mora s~tur~bed wibh moi~tureO Dryi~r.~, apparR~Ils0~ ~
oommo~ u~e ~ pre~nl; ~ e~peo~lly bhe one~ ~arvln~ ior d:rylng a rale.tivel;y b~ ~mounk of produc ~ u~ual~ d~r ~ith he~bed ~ir o~ ~mall relative humldit~sr 9 whloh -1 relea~ed inbo bhe atmo~phere aftar bhe dryin~ ha~ t~lse~
plaoel, Thls opsn ~R~ ~raam dxy~ng i~ a~ompanie~ b~
~i~ni~i~anb lo~ of thermal energg g ~nd lt 1~ un0~ti~ bo~
also ba2ause in ~ome e~e~ the p:rOdll~Sb9 ~0 bs drled are heat-sen~iti~3~ It ~an al~o be di~a~l~an~ eou~ be~u~ of ~rodu¢in~; air- pollut ~ o~, It wa~ pre~i~ely the heab~eIl01tivity o~ ~paeial produ~t~ (mealclne~g ge3:abl~e~ ~ood~b~$ ;, et~ hioh m~de dxying w~th lo~ t~og- en~ironment or und~r e~ro~m~
tem~rature ea~ ne~ea~ryO ~he ~mall re~bi~e humi~ibg o~ low tempar~ure ~a~9 whlch i~ ~ p~eregul~ite o~
e~fe~t~e dry~, o~ ths~e k~ 3s oX ~c3uot~y ~an b~
~hie~ed bhrough diminl~hl~ the ~bsolu~e humldit;~ oX
~he g~ herePo ha~ bee gge 0 P~en~ Noc, 39257~,73? bh~t the ~ a~ 1l3houla be ~o~ e~
h s~ lld a~orb~ hi~ h~ x~ n ~
0~ ~ht3 ~g8,8t, It h~ o been ~Ugg,eBte~ ~i30~ Au~ri~n ~Hrl~ o ~17~85~ ~a ~ 8h. ~ J bo o~ r ~h~ 13 ~ m~ h~

~.

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L3~03 ga~ i~ bhi~ man~er m~ke~ ~ slo~ed ga0 ~tream al80 ~pplioable~
~he ~ùggesbed ~olut~on0 utiliz~ng 3 de~l:iGc~nb liquld caWE o the liquid ~o conbaab w~bh the e~ abream ~ ~pra~ed or pulveri~ed ~orm~ ~nd the liquid p~rbi~le~ 4arrled e.wa~
b~ g~s 6bream ~re held baok bg ~ drip gepar~bor,. 8u~h ~g~bem ~rom the point o~ ew o~ e~0r~;ebic~ i~ th~abl~all more ~avourable th~ the one worlc~n~ wlth he~bed air e~sellbi ~lly beoau~e bherm~l 10B~ o~u3ed b~ bhe ral~a~g o~ the a~ r inbo the ~tmo~phere i~ omitbedl, Still / up ~ill no~9 clo~ed gas ~ir~ul~tion sy~teins have only been u~ed i~ caae o~ special drylng problem~9 an~ ~qh3never 1~ ~a~
possible with re~ard to the ohar~cber~ti~ o~ the produob~
to be dried9 the ope~ a;lr ~tre~m method wlth heated ~ir was appliedO q~he rea~on for lthi~ i~ thE3t ths tradltlonal t;s~pe of closed ga0 olrcul~ting dr~er~ maksa a ~o~tly investmellt ~ the oircul~tion o~ ~ery mueh ga~ ~ ~ extremel~
ener~ onsuming, and bhe de~lecanb liquid used ior regener~blon 18 ~p~n~i~e; the~e l~t~ers re~ult ~ h~h operatin8 ~pe~e~
It ~ ~he m~i~ ob~eot o~ ~he i~ve~tiQ~ to provide a olosed ga~ sbream drier whioh a~ ~ar a~ ~p~e~ a~
oo~oarned i~ more f~vourabl0 tha~ bhe pre~ou~ ~le~ed ga~ ~:
-~r~m a~ Ompb~ V~ w~.~h ~h0 ~n~w~ ~p~
m aryars 9 a~n 1~ ~a~ u~ od~
~,o be d~,d~, ~
~h~, inv~ on ~ ,h~ çw~n~ o, Con~act between ~,he ~ r~ and thi~ id*~o~,nk ~u~d 3hould ~ ~h~ u~ b~ pul-æ~ he ~u~d bu~ he ~ u~

contacting device placed in the path of the gas stream which allows the separation of drying space and contacting space as used till now to be eliminated.
(2) In a closed air stream circulation system the amount of air to be used for a particular purpose is a multiple of that used in an open system. For this reason, the gas contacting device using desiccant liquid and the product to be dried should be placed close to one another and in such a way that the air stream should suffer the least possible alteration in velocity and in direction in the course of the circulation.

(3) Drying should be carried out not with low but with such high temperature gas stream as is allowed by the character of the product. To do this it is expedient to heat the circulated gas stream by the desiccant liquid.

(4) When regenerating the desiccant liquid the evaporation heat of the steam eliminated from the liquid should be recuperated into the liquid to be regenerated with regard also to the heating needed during the regeneration.

(5) The desiccant liquid gas contacting device should be of a structure that can also be modularly arranged, and permit the application of the per se known principle of counter-current at the drying of continually moving products.
Hence, according to one aspect the present invention provides a method of drying products comprising the steps of introducing the product to be dried into a drying compartment;
continuously circulating a drying gas stream so as to cause it to pass past the product to be dried, contacting the drying gas stream with a desiccant liquid to remove moisture from the gas;

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and regenerating the desiccant liquid by circulating at least a part of it through regenerating means to remove moisture therefrom, characterized by producing at least one layer of the desiccant liquid at the boundary of or within the drying compartment, and traversing said at least one desiccant liquid layer by the drying gas stream.
The use of a liquid layer according to the invention is advantageous in several respects. First~ it renders unnecessary the drip separator applied in the known systems, all the same it prevents radical pollution of the gas stream by the liquid-drops, and thus it diminishes the loss of the desiccant liquid, too.
Second, the coeficient of the mass transfer between the liquid and the gas is more favourable than with liquid particles; this allows the use of a compact structure accompanied by a smaller pressure drop in the gas stream. Third, it does not demand a contacting space separated from the drying compartment; the liquid layer can be established quite close to the product to be dried.
Another advantage is tllat bringing about a liquid layer is less delicate an operation than spraying as known from the previous solutions, because the danger of a block up is much less~ and so is the need for maintenance. This latter factor is of particular significance as the gas stream often transports dust and other pollution besides moisture into the desiccant liquid, which blocks up the holes in the spray nozzles.
An advantageous implementation of the method according to the invention is to produce a substantially horizontal desiccant liquid layer9 and bubbling the gas stream through said horizontal liquid layer. By this it is possible to dry bulk goods, _ 5 _ ~3~

for instance transported on a belt conveyor which is conducted under or above the horizontal liquid layer.
It is another extremely advantageous implementation of the method wherein at least one desiccant liquid layer is produced by causing the desiccant liquid to flow on liquid film conducting elements arranged in at least one plane at the boundary of or within tlle drying compartment, and said contacting is performed by causing said drying gas stream to pass between said liquid film conducting elements. The liquid film conducting elements can be applied to form a curtain-like arrangement which may for example border the drying compartment.
According to another aspect the invention provides a method of drying products comprising the steps of moving the product to be dried through a drying compartment; continuously circulating a drying gas stream so as to cause it to pass past the product to be dried; contacting the drying gas stream with a desiccant liquid to remove moisture from the gas; and regenerating the desiccant liquid by circulating at least a part of it through regenerating means to remove moisture therefrom, characterized by bringing about continuous heat exchange between the desiccant liquid and the product to be dried so that the heat is transmitted by the drying gas stream between the desiccant liquid and the product to be dried.
It is practical to raise the temperature of the desiccant liquid during regeneration to such a degree that while contacting the desiccant liquid with the drying gas stream the temperature of the gas is raised to a predetermined temperature, preferably over 40C, for heating up the product to the degree required. This

- 6 -~L3~ 3 method provides for the possibility oE diminishing the quantity and velocity of the gas to be circulated because at a higher temperature the quantity of moisture extractable with 1 kg air is increasing, and allows an efficient recuperation of the evaporation heat of the steam evaporated from the desiccant liquid during the regeneration into the desiccant liquid to be regenerated. A further advantage is the omission of cooling applied in the previous gas-liquid contactors; this results in a simpler construction of the gas-liquid contacting device.
According to a particular execution of this method the desiccant liquid is a desiccant solution; said regenerating is performed by evaporating the desiccant solution; and the steam evaporated from the desiccant solution is at least partly condensed by the desiccant solution to be regenerated. This permits highly economic

- 7 -regeneration during which energg requirement o.L' regenerablon c~n be xaduced ~t a gr~t e}~ent by appl,ying a multi-eïïact;
boilin~ or B multi-~t~ge f la~h evaporR~ion. Comp~r0d to the previous ~3olut~on~3 wher~ ~he evaporatlon heat o the evapor~ted ~team 1~ used ~or heating the ail~ which is to predry bhe produc t ~t i5 an advanta~e ~ha~ ths ~ts~m conden~ation with ~ li(au~d requires ~ ~m~ller and ~heaper deYioe th~n that work:ing witih l~ir, Ib i~ pr~c tical to boil khe de~ioGant ~olublon ko be regen~rs,t;ed with the ~team e~aporabad îrom ~he ~olut~ on durin~ regener~tion. Energy reqlliremenb can be roduced through ooncentrat:Lng the ~esioca~ olution by multi--effe¢t boiling, ~nd usin~ th0 incomin~ ~olution ~o ~e evaporated for conden~in~ at least parbl;y ~he ~team evaporated durin~ the fir~t or d~ring th~ la~t bo~l~ng process of bha regenerabionO
Rege:~eratioxl oan be ex~cu~ed by heEIting bhe ~e~ n~
solution to ba re~sener~ted without ma~Lking 1~ to boll, wlth ~he s~e~m evapor~te~ ~rom the solution. In thls Ga~e lt i~ partl~ul~xl;~ ~dvanb~geou~ to re~6nerate ~he de~i~ca~b ~oLutio~ wibh ~ multi~age ~la~h ev~apor~toxO
~ Gording to ~ ~eI~ adv~ntageou~ plem~ntatio~ ~1 th~ m~thod of the in~rentlon, ~he de~i :scan~ ~ol~tion i~ bo d b~for~ rQ~0~io~ un~ h~
dow~ of ~he d~ e~nt ~olutiol~ duri~ ~he ~rying pro~es~
~o ~ha~ ~he ~ nl~ ~o~ o~ r0~ d d~rm~ d ~p~:~0,t~lr~O T~ ~oo~ u~g~ d h~
v~ ~th~ ~n~ o~ t~ ~h~ n~ ~o~ r ~3~33 and is meant ~o complellient tho cooling down which occur~
in the desiccant 501uti.0n ~t contact with the dryin!, gas stream. ~he d~gree o~ cooling must ~e ~lltered ~or ~nst~nce accorclir~ to the sea~on~ ~he coollng i9 prefer~bly done during regeneration"
According to arlother advanta~oll~ imp~!emerltatic~
of the method the continuolls circulati.on of th~ drying gas stream i9 performed by conductin~ the dr~yin~ gas stream in a path sec~ion ba~ween the pro~uc t to be drled and the desiccant liquid 9Q thQt in ss.id p~h section bhe ratlo of the rllaximllm anci minimu~n veloci.ty o~' the drying ~as ~tream ls smaller than five to one and tha alter~tion oE the dlrection o~ the drying ~as stream is less than ~0 degreesO This measure r efiult,s in a relatively small demand ~or ventilatlon po~Yer, this ls an important polnl; in the economy o~ the whole drging prooedure~ Ths ventilation po~er can be furt;he~ di;ni~ had i~ th~ drying gas stre~m is conduoted betw~en the produo~
to bo dxied and the desiccant llquid substE~ntially ~ikhollt any alteration o:~ veloc ity an~ direction~, It is practical to u~e ~ir a~ drying gas and s.~uaous solution of calcium chlorid e a~ a da~i~cant ~oluti.on~, ~he c~lciurll chlori~3e aolution i3 par~i~ular~y pro~it~ble owing to ~t che~pn0~s,, The mq tihod ~c~ording to th~ lnvention 1~ applic~bï0 not only for allminating bhe molstur~ of w~or bu~ ~190 ~0~ dxyln~ mate:rial.s whioh con~ain a di~erenli kirl~3 of moi~ kur~ b~,7 USil~ n appropri~
ds~iccant 1i~U;.~O Ilt i3 po~ble~ for 1r}Pt~ e; tO a~p3;~

~L13~3 the pre~ent method ~or d~ginK ~lteriRl~ containing alooholia moi~ture using clo~ed air stream ~nd peb-rol as de~icc~nt liquid~
~ ccording to a further implementQtion of the method bhe drying g~ stream consi~ts o~ ~t le~t t~o parallel partial e~ stream~; the product ko be ~ied i~ moved ~cross ~aid partial gas strearns and each of said p~r~ial gas strea~s i~ contacted with a de~iccant liquid o~ ~pecifio concentration Rnd temperature. In this way the drying pro~ram for the product to be drled can ble extremely ~aried.
For insbanoe, according to R highly expedienb implementation of the method~ each of said parti~l ga~ ~treams i~ contacted with a more conoenbrated de~iccQnt liquid than the desicc~n~
li~uid contaoting the pravious p~rtial ga~ ~trsam with r~spect to the direction of movement oY the product bo be driodO Thi~ result~ 1~ a counter~c~rrent between the product to be dri.ed and ths de3iccAnt liquid~
~ he method according to ~he i.nvention can be implementsd also b~ pxod~clng at least ~.vo sop~rated grou~
af desiccan~ llquid f~ms of ai~feren~ concen~r~t~on, plaeing ssid group~o~ da~lsc~nt ll~uid ~ilm~ ~ide by side 1~ t~e wa~ o~ eald partial ~:7,~S stre~.~ns so that each o~
~aid ga~ ~tre~ is cont~c~ed wlth it~ own at l~st one g~ou~ o~ d~siccant ~uid ~llm~. It i~ an ad~ant~geo~
implementat~n whore~ e~ch of s~id igro~p~ of ~eslc~ar ~ d ~ilm~ ia prov~d~d w~th own llquid c~rsul~t~on; the l~.gu~d o~rcul~ion of th~ ~as~ ~oup ~lth respa~t to 'r~he dlre~io~ o~ mo~men~ o~ ~h~ p~odu~t to b~ ~ied i.~ fed with the regenerated desiccant liquid coming from said regenerating means; the circulation of each preceding group is fed with the overflow of the circulation of the subsequent group; and the over-flow of the circulation of the first group is conducted into said regenerating means. In this way counter-current is attained between the desiccant liquid and the product to be dried.
It is also possible to move the product to be dried across the partial gas streams and alter the temperature of the product in a prescribed manner through controlling the temperature of the desiccant liquid separately in each individual group of desiccant liquid films. In this manner the drying temperature also in case of continuous drying can easily be programmed for each phase of drying.
According to a further aspect the invention provides an apparatus for drying products comprising at least one drying compartment for the products to be dried; at least one contacting device for contacting a drying gas stream with a desiccant liquid to remove moisture from the gas; gas conducting means for conduct-ing the drying gas stream in a substantially closed path through ~0 said drying compartment and said at least one contacting device;
gas circulating means to cause the drying gas stream to circulate along said closed path; regenerating means for removing moisture from the desiccant liquid; and liquid circulating means for circulating at least a part of the desiccant liquid through said regenerating means and said at least one contacting device, characteri~ed in that said at least one contacting device includes means for producing at least one layer of the desiccant li~uid to be contacted with the drying gas stream; said at least one contacting device being located at the boundary of or within said drying compartment and being disposed across said path conducting the drying gas stream.
In an embodiment of the apparatus according to the invention the contacting device comprises a vessel for producing a substantially horizontal desiccant liquid layer, said vessel having on its wall bubbling caps for bubbling the drying gas stream through said liquid layer, said vessel being connected to said liquid circulating means so as to cause the desiccant liquid to flow along said vessel, and said drying compartment is located above or below said vessel. Preferably the drying compartment comprises a device for transporting the product to be dried through said drying compartment, said transporting device having openings for letting through the drying gas stream but not letting the product to be dried drop.
Advantageously the transporting device is an endless belt conveyor, and said gas circulating means are ventilators placed side by side along said belt conveyor.
According to another embodiment of the apparatus the ~0 contacting device comprises liquid film conducting elements being placed so that the drying gas stream is passing between them, said liquid film conducting elements being arranged in at least one substantially vertical plane at the boundary of or within the drying compartment. A high degree of operational safety and simple structure can :-. :

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1~3~

be achleved ~ the contia~tiing device .l~urther ~ompri~e~
recepta¢le for r~cei~:irlg and holding the incoming de~iGGan~
liquid, ~ least one pil~ lock to guide ln l';ilrr~ form the liquid oub of ~;aid reoepbacla, 1~ quid diYtri~u~ing mean~
havin~ at lea~t one d:L~tributing surface connec~ed to ~a:ld at lea~t one pile lo¢k and facing ~ownward~, end liquid outlet means~ wherein ~aid film oonduct;ir~, elemenlis are connected between said liquid di~tribQti.ng ~ur:E~ce and ~aid liquid outlet mean~ ~o khR~ they conduct liqu:id film~
from ~aid surf~ce into said ou~let mean~. This embodiment i~ ~ot very ~en~ibive to the pol].u~ion which might get into the de~iccal1t liquid ~rom ~he d~ing gas ~tre~mO It i~ pra¢bi~al bo arrange the liquid film conduc ting elements - pre~or~bly strip~ or :Eibres - into at least OJIe substRntiall;sr vertical pl~in. ~here is ~n e~cellent hsat-~nd mRs~-txan~Iex be~we~n ~hs desiccant l~quid ~ilm~
cre~tea on the thin ;ibr~s ~nd the dryin~ g~s stlle~m. ~he ~brlps or fi~xes can be mRde o~ a met~l. resl~t~nt to the desioc~nt liquid or o~ a pl~stic material ~hich tolerato~
the highest posslbl0 terrlper~bur~ of tha de~iccRnt liquid, One possible embodl~enl; of the dr;yin~ E~pparabu~
s¢cording to the in~ention i6 ppll c~ble f or product~
~ood. ~his smbodirnen~; compri~e~ a b~ement;, a ~h~ roo~
and R f~l~e roo~ pro~ded with openinK~ ~o~ tti~g l~hroug~
the d3~ing ,,~ ~tr~am ~n~3 located be~we~n ~id t~a~ement and ~ald æhe~l~roof, whe:rein ~ld dryi~g ~ol~partmanit is lo~ted b~wea~l ~ald ba~me~t ~nd ~id .~ sa roo~, ~ald ga.~ ~:lr~ula~i.ng me~n~ are ~re.rltilator~ placacJ between ~Ald ~3~ 3 -- 14 ~

false roof an~3 sai.d shell-roo~ nd ~ 1 ¢onta¢tin~ devioe i~ pl~ced at f~aid dr,yi r~; compartmerlt rjo til)r1 t ~aid a~
p L 1~

le~st on~ vR ~tic~ orm~d b,y ~aid ~ id ~ilm conduct.l1~, e].en1ent3 ~tl ~ubsta1l~Giallg perpen~-lcul~r bo the dryin~ gSlf, stil'eam alld eXtif:llC~s b~t~aon s~li.f~ bnSerl~ent and said ~'alse rQf~E. Il1 .r~1?G~1 a1l ~rr~ngf~3merlt tl1e li~1uid film ~s cont~ctiry~ dev:ice ii placed Qt a houn~:1ar,~ sur~aGe or El cl~0~ ~Jectiorl of` t}l~3 dryirlK comp~L~ e~lt~ ~.id ~r~QC~
or croE33 sec ti:ior1 beil~; suhstanti~3lly pe-rpetldicular ~o tho dire-~tion of th~ 3 ~ltire~m~, ~rhl~ RrrRngement; guarantieo~
libtle pr~ ure cIrop i ~ the I~3 ~ream which resultis in a low eller~y con~urnptilon due to ~he ~reJ~t,il~tiionO
A ver~y advantageoll~; embodi.men~i ~?~ the apparatu~
accordin~ to tl1e inve11tlc3n i~ wher~in the contactir1g d9V~
cc)nsi~b~ o~` Rt lea~t two l:lcluid i`i.].m modules pl.ac~?d slde by side ~ each 1 i~uid filrIl module ha~3 its own l.lguid film oor3duo~ eleIne~ e, ~nd o~n ligui(3 o:~ rcul~i.ng ~levi~e providin~; a liquid c~ culat;ion to fo:r In the li~uld film~
on ~id own conduGtin~ elernents, and fia.I.d l~qui~ fl:Lm module~ al~e pro~rid ed with ~ corl~morl llqI.I 1d ~harl~lol ,~i~rW
0~ecbil3J ~,~id lli~lui.~ ciroul~1iing devlce~ a conu~
liguid c3ha~J1l~?1. iteir~ conrl~Gted ~o ~3ai~t liçuid ci:r~ul.~rlt.,~Ilr m~n~30 ~hll~;3 ~:h~ t~pa~ .U3 h~3 o~ ~3~.n~ 7n~r~,~1n~
~n~ be~o~ .?l~ t~ i~ t ~ ch 1~ i3 ~ 310~iU~ 7 ~b~-e~3ic~a~ 1.d who~e activi~;y i~ dif~:rent .l~l~m th~ti 5 ~ L ~ r E3 ~

~ ccord1 ng ~o a further embodimenb bha ratio of ang two ~lo~ ~ection~ o:E ~aid ~,B~3 conduo~ing me~ns between ~id dryiry~ comp~r~ment and said corltiacting devlGe i~
between 0.2 and 5g ~nd said conbactinp~ devica i~ loc~ted a~ ~aid d~ying compartmenb 80 that the drying ga~ ~tream is ~lowing bebween the produc b bo be dried and ~aid contacting device with a d*rection~l change o~ le~8 bhan 30 degree~, It i~ very advanbageou~ if said flow ¢ro~
se~ion ratio i9 b~aeen 0~,5 and 2,9 ~nd said direotional chan~s e i6 ~ub ~ bant i~l ly æero d egree s, aJla the d i s bano e be.~ween said dryir~ compartmant ~nd said contacting de~ioe i~ les~ bhan the hydrauïi~ di~meter of ~a~d ga~condu¢bing me~ between th~m.
~ ccor~ir~; to a h~ hly pro~:Ltable embodlment oï the apparatus the de~iccank ~olut~Q~ re~enerating mean~ oon~ain a mlllti-s~fe~t e~porator or a mlll ti -s~aga fl~sh evapora'so~.
It i~ the latber which :is mor~ e~ped:lent w~th :reg~rd to :It~ ~imple operabion~, ~hi~ emboaime.nt guar~nt~a~ va~
e~onomical rs~eneration al~o X:rom the point o~ ~i9~ o~
~ne~g~p ~orlsumptionO
B ~urthe~subjecb matter o~ bhis invention 'i~17 aE
rtiole of' rnanufa~tura,, ~he producli prepared acoor~1 to tha p~ent me thod Furbher det~ils of th~ entlon wi.ll be do~r~be~
b~ tAk~llg re~exonce to the ~¢¢omp~ draw~ whi~h ~how~
b~ wa;y o~ exæm~ ;, embed~ ent~ oX the apparat~ c~or~3i~
bo the inv~rltlong and ~ whichs ~'~

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Fig. 1 i~ ~ ~chematio illu,tr~tion of a .fir~t- embodlment of ~ drying apparabu~ ording to ~he invenblon ~ig. 2 i~ a ~eational ~riew OI e~ ~e~ond embodiment oi the drying appar~3tu~, ta3~en ~.lon~ ~he L~ne B--B
o~ :Fig ,. 4 ~
Figl. 3 is another ~ection~ s~ o~ the ~eoo:nd embodimenk, t~ken along the line ~ o~ Figo 4S
Fl~,. 4 :1~ a bop ~iew of the ~econd olnbodiment of ~he drying Qpparatus shosNn in Fig~. 2 ~nd 3S
Flg. 5 i8 R ~eo~ional ~er~pe¢b~e view of a third ambo-3imenb of bhe dr~ring appRr~bu3~
Figo 6 i~3 Q. f;ect;ion31 top view o~ bhe third embodime2lt"
t~ken alOtl~; bhe lino C---~ of E`ig4 59 FiB- 7 i~ a ¢iXCllit dia~ram o~ the de~iccaxlt ll~uid re~ellerAtor of the second embodimont ~B 8hOW~I
in Figs,, 2 ~o 4;
. 8 ~nd 9 a:re circuit diagraol~ o~ two okher desi¢Gant liguid regenera~or~ ~ppllcable ~n the d~yin~
~ppRr~tus accorain~s to the ln~ention"
F:4~. lO i~ ~ ¢ircuit dlagra~n of a nlulti ~k~ge ~la~h a~aporskor applic~hle ~ R de~ nt liq~d re~ensrs.kor i3~ ~he drying~ appar~tu~ Qrdl~
to th e inv ent ion"
8s.me re~eren~ chara~ter~ refer to ~De er ~imilar element~ ~h~ou~hou~ the draFJing~O

~!L3~ 3 In Figure 1 a casing 42 of a drying apparatus is shown schematically. In the apparatus a gas stream e.g. an air stream which dries product 50, e.g. bulk goods as shown in the figure, circulates in a closed circle in the direction o~ arrow 64.
Circulation is forced by a ventilator 66 which is driven by an electric motor 46 placed above a false roof 54 shown schematically, without its holding means in the figure. The false roof 54 has openings 47 in it which the air stream can get through. The product 50 is situated in a drying compartment 40 under the false roof 54. After flowing through the product 50 the now wet air strea~ gets into a contacting device 43 which causes the air stream to contact with liquid films 41 of a desiccant liquid.
The desiccant liquid is forced by a pump 141in a regenerator 150.
The active and hot desiccant liquid comes into the contacting device 43 from a pipeline 44 above, it gets into a pot-shape receptacle 55, from there over a pile lock 56 to a liquid distributing surface 57 facing downwards. From the liquid distributing surface 57 it gets onto downwards directed liquid film conducting elements 58, e.g. fibres, said elements conduct it to a liquid outlet channel 62, from there it departs through a pipeline 45.
The desiccant liquid diluted and cooled by the contact with the air stream gets into the regenerator 150 through the pipeline 45. The regenerator 150 displayed in the drawing as an example contains a multi-stage flash evaporator 151, a liquid circulating pump 141, a pump 142 " . ~ .
, , ~ .

1~3~3 for removin~ the distillate of the multl-stage ~lash evaporator 151 ~hrough a pipe end 149, arld R h~at-e~changer 143 which i~ feeded with cooling wRt0r through pipe en~
144, Cooling in the heat-exchange:r 143 is e~sen~ial ~or ~he appxopriate operation o~ ttle multl-~tage Elash evaporator 151. The act~e liquid lea~in~ regenerator 150 warms up while ~oing through condenser 145, then gets b~clc to the contactin~ device 43. The condenser 145 gets the heating stealll throu~h a pipe end 146, and the conden~at~
i~ carried away by a pump 147 through a pipe end 148.
Elemen~s of the regenerator 150 and the heating a~ter the regeneration are well-known i.n themselv~, so their detailed de~cription is ur~ecessary.
~ he embodimen~ accordin~ to Fig. 1 is particulQrly advantageoll~ when dryir~ products with hi,r~h heat tolerAnce e~gO bricks, as in thls arrangement the t~mperature of the desiccan~ liquid which ~la~ returned from the oontactin~
device 43 and has been "cooled" there i9 still enough ~or eliminating the moist~e duril~ the flashing procescs~
~ pplication of the multi~stage flash evapor~tor 151 shov~n i~ Fig. 1 i~ particularly a~YantageoUs in th~
apparatus according bo the invention because it i~ ~ro the point of view o~ controlt opera~ion and reliRbilit;y more ~avol~able then other multi-effec~ e~apor~kor~ ol' the same energetic el'ficiencg. ~ere the evaporatlon ~0~3~1 not take plRce along heat transfer surfaces~ ~o it i~
less sensitive to enc~u.station an~ Gorro~iony and i.t~
construction doe~ not become compliG~Itea ~ven i~ en~:Lp,e3~l.n ~, ~:
. . ' , ~ 19 --o~efeGti~ y ~ mprov0~, Natuxallg, ~ evapor~kor o~
di~ereIl~ ~rrangemen~ or Con~tructien p~r .qe know~
~gually bo applied for the regenç~r~bio;n.
5imil~rly~ bo u~e the contac~ing deYice 43 as showx in Fig. 1 in the ~pparat~ c~ording to the in~entio~.i~.
~rerg pro~ibabl~ ~his co~sbruction :~ ns~t ~e:n~itive to the pollu~ion ~;ett~ into the liquid from ~,h~ air ~tre~m, sn~ guaranteo~ the oontact be~ween bhe liquid ax~ e ~:lr s~ream to h~ve a ~;ood heAt- and m~.ss-~rQns~ar cos~ enb,, I~.tho ~pp~rs,kus according to bh~ :Invention the drying compartment ~n be ~on~tructed and the pro~uct 50 to be dried cal~ be pl~ce~ in ma~ wa~s (~uspended~ ~luia--bedded~ ge~y~er" ~hamber~ tu~nel or anyth~ng else)r The product ~n be mo~ed d~ri~g bho dryi~ pro~e~s ~n~ the drying gas ¢~n e~u~11g meab th~ produc~ks irl counter-$, C~OSS ~r ~r~ urr~
Figi, 2 ~ 3 ~nd ~ ~how ~uch ~n embodim~sn~ o~ the drying apparabu~ aocording to l;he i2l~ention whlch ope.rate~3 with a subst~tl~lly hor~zo~ll;y moving liguid la;yer 1 and with ~l~o horizo~ll;sr ~vi~g pr~uc b 2 ~bo~e th~
liquid layer. ~he product 2 e~gO ~o~bea~ ~hroll~,h ~ ~hI~oA$
3 g~t~ onto ~ tran~porb~n~ d~oe9 ln the a~wi~ ~ bel~
~on~Ie;~orO ~h~ h~ ra~3m~ u it whi~h le~ the ~lr through bult pr~ent the p~du~t. 2 ~om :~al 11~ of io !l~hs bell; ~ i~ held b~ ~o ~heeï~ 6 w31ich are col~brllct~d to b~ ~ap~:l.e o~ ~tretchin~
dx~ring ~he belb~ :Eor thi3 purpo~e e.g,, ~hey c~n be i~t~d.

or ~ub~eriæed" O.~e of ~ihe wh.~ 6 i~ dri~?~rl ~y an ele~b.r.~u mobor 8 ~hrough ~, dr1~in~ ~g3~r 7~ The lo~de~l belb 4 o.~ h~ be~ on~ 0~ traIlHportE3 tJhe produc~ 2 ïrom tho th~oat ~ ;rc~ugh ~h9 dr~lng compE~I ~m~ t 25 whlch ~i~ua~d i~ h~ a ~ ar~ , '5h~3~
through g~e 10 tr~n~po:r~ it to\~uolleog;or 11 f:rom where bhe d riod p~O~3~lC~ i.s -~ir~n~por~d ~o ~h~ plaoe O:e ~box;l~
or u~ tio~ b~ el~ ~onYeyer or ~ p~ g .~.o~ ~how~
1D~ tho f igure~ rrl~e empt,y skr~.n~ of ~he bel~ ~30n~eyor p~sses Imd er ~h~ ~slng 9 ~n bh~ d~r ~h~ d~
and o~ b~ n~te~ fh~ .n.,~
!3pQC~ 1~ f~ ,?~ ~hi~ b~ O~f3f'~
~he belt ~o.~o~ Lf~ d ~ 3 f~ 3f~ 3.-3~ f~,n.t ~ ui~ f9~ ih.~f ~ b.rs'2e'~
Q~ 33 f~ h~ 3~ f.~ .h~ h ~ f~
f~ io.L~ W l~ft f9i,bi~

~h~r~ i~s -f~ Lr ~ t~ r.~ f~ a E'~
~ ? ~L~ f"~ 3~ d ~7 23G f."~ s~ ;fl 3.0~ .f~ h.9 O ~lf~ . f'3~ s ~ pf~;~'kq~3 ~f~g ~
f~f~f ~ d f3~ ~rLd ~ ~h ~ f~rf~f~ f~ r~ f, f;~ Qf~ ,S~ t? ~Lf~ ~ 3 i~h ~f'~'3 ~ ~f`3 ~ i $.~ f',~

~1 :113:~L903 o~ ths liguid ve~s01 13 ~ one of bhe G~p8 20 ~ ho~
~ ~ magn~ied form i~ Fig. 2 - inbo bhe ~e3i~anb 1~ aul~S
lager 1 ~n ~he di:reckion o~ arrov~ 219 the~7 leav~ ~he li~uld l~yer 1 through ~he openin~ 5 o~ bhe belt ge~
into ~he lay*r ~orme~ by the prodQ~ 2 to be drl0~, E~d ~er goi~ throu~h i~ the air go~ b~ck to ~he ~pper ~ir ~ollecting ~paoe 16, bhus bhs air ~ir~le i~ ¢lo~ed. ~e liquid ve~sel L3 which ~ prov~ded w~kh b~bbîi~g CQp~ 20~ -i~ this embodiment function~ a~ a ~onbaot:i~g d~i~e 43 ~hioh brinæ~ aboub contaot bebwsen ~he alr ~tream ~d ~he deg:Lo~a.~ 1~1 9,11i~1o ~ ha îour ve~tilator~ 17~,, 17B, 17C a~d 17D bri~g ~boub Xour close~l~ circulating ~?arbial air ~tr~am~ he ~irs~ p~rkial ~ir sbr~am goe~ through ~ ion por~ 2~ ~
and meets the ~:rr~ t pxo~u~b 2, ~he ~econd o~e goe~
through suctio~ port 22C~, th3 thlrd bhrough ~u~tio~ port 22B and the ~ourbh th~ugh ~bi~n port æ~,, a~d ~hiæ 18~:t o~ ~tra~ts ~rom p~oduct 2 bhe 1~ par~ o~ mo~kuxe to b0 extra~tod~, ~he ae~i~¢~t liquld ~f3t~ o bhe li~u~
~e~eI 13 throl~h pipe-~oin~ ~6 ~nd ~ep~rt~ ~hro~h p1pe-~oi~ 27~, ~he arr~in~ ho~ ~nd a&t~ 1iqu~
bubb10d bhrou~h b;5 t.ha alr o~ bhe 1~ aælbia1 tir ~tx~m~
pa~ a ~ 3d B~f ailu~d l~QU~ i8 bu~a~
bh~ y th~ 8$ p~ r ~ m.
~.T~3ill~ B~ Xe~l~ p~r~i~1 a~r ~0~ b~ ~b~
n~ k~r~ ~:7~ o~
~d~ g~0~l3 wl~ r~p~ to ~ m ~ d;~ b~

~ 22 ~

b0cause o:E ensuring cou~ter-cu.rlerLt c~:r~ing with th0 produot 2 ~nd the desiccEmt liguid 1. moYing, opposite to o~e another~ Il; i~ obvious th~t if there were o~ly one ~i~le air str~am circulatad by one ~Tentila~o~; ther~
would be no counter-curr~nt d~ging in spite of the produc t 2 an~ the desiccant liqui~ 1 movlng ~n eppo~ite direcbions. The counter~current e~ect ~ould ha~e ~Ln optimum a~iciency i~ ~here were an endles~ mber o~
p~rtial air streams circul~ting side by side., II1 this respect it is e~pedient to use ~s many partial ~i~ ~3tre~ms as possible at ~ryi~ accor~ g to the inventioll, Ik ~n be seon in :~igs~ 2 to 4 thf~t dx~in~, compartment 25 and the ooIltacting de~ice 4~ al~a pl~ed immedis,tel~r abova one anothsr qua~i ~ormi~ t`lWO 1~ oor~;W
o~ the casing ~,, Another em~od imenk o;E the ~m~ t~ppo o~ a:r~ em~
di~rent ~rom ~he embodi.me~t showrl i~ F~ ~ to 4 bhat ~:he llqu~d ve~s~ is pla~e~ abo~e th~ l.o~de~
~h~
o~`fb~ oXl~y~3xO ~hi~ t~a~u~ ~h~ ~h~ p~
~onba1n~ su~h 1it ;~1e par~1clà~ ou.L~ h~3 11~u1a ~es~e1 13 through ope~i~ 5 ~ th~ be1t 4y and wou1d pol1ute ~he Ege~ios~t 1~ qu~ ~b ~ un~vo-~r~
d~gr~3e. I~ ~uch M~l smbodiment the ~ir ~tr~am ~nt;~iY~, ~hrou~h openi~g~3 19~, 19:E~, 19G ~nd 19D ~o~ald ~irs~ ~o ~hrough ~hi~ produ~ t 2 g then ~chrou~h ~h~ y~
~no~he~ ad~ tage o~ thi~ embod 1ment is ~ha ~; p~ 1e~
~he ~rodllot 2 fa11~n through op~ning~ 5 c.~:~ t~e be~t ~3 --~ 31~3 ~ be ~ollec~ on the boktom o~ khe ca3:L:Ele 9 and ~rom there ca~ be tr~n~ported awa9 as dri~ pxo~uct ~rom bime to time or ¢on~i~ua lly . It iB al~o advantageou~ ~hat l~quid drop~ which might ha~Ta been ca~r~.ed aw~y from t;he liq~id lE~yer 1 by the Air ~tream, do no~ ge~i onto prod~c~
2 but ha~ng go~e khrollgh ventil~tf.~r~ 17~9 1713~ 17a and 171~ can be colleGted in pot~ or in ch~,n:nel formed in.th0 bottom o~ ~ub~; 18~9 18:B~ 18C ~d 18~)9 ~,nd ~rem thers c~ be ~eeded ~ack to bhe liquid o~ rclel, In the embodiment displaged in Figs., 2 to 4 the pollut-ion which had ~;o~ ;~to ~he liqui~ lay~r 1 e,.g~ .~xom ~he produc~ 2 ~;hro~3h op~7ngg 5 ~ . be ellmln~t~ w:~h ~he help G~ a :ep~r~ting tank well know~ ~n it~el~ wh~.~h is in~erted into I;he desiccan~ liqu:Ld Gircle p~e~exab~y .
a~ter pip~ aoint 27 in ~3uch a wa~ o;r example~ tha~ kh~
liquid pouring into the ~epar~t~ng t~nk can. on~ ~epa:~
~hxo~gh op~ings pl~ed at hal~wa~ bo th~ 1l ht3~æ.h~
o~ th~ l~id le~l in th~ t~nkO ~aturally~ ~h~
be cle~d ~pp~opris.~el~ 9 ~h~ ~luid mu~t ~e ~l~imm~ J
depo~i.t~ mllst be ~emovedO
~ he d:Lluted de3ic~ant; 1~ ~i d ,, i~ bh~ em~ed~e.~ .
da~ u~o~ ~bs lnt3 t~ r~g~n~ o.r~
o;~ e embodiment ~hown ~n Fig~l, 3 ~d 4 ~ to ~ ~olu~Lo~J.
~gtend~nser~ which ~on~ o~ a li~uid ~ir~3uï~nc~ r,~
r c~nd~xl~er ~9 wh~ ol.~3~ bg 7.~3d ~ollltiioxl9 a pump 30 ~or rerno~lng th~ ;t il ~ 3!9 h~ 3d ~v~por~ ~or 3L ~d a pu~n~ h~
~um~ ~he diLuted solu~ion through eo~ldens~ 9 a~ ~ ~o ~ ~4 ~ ~ 3 medium9 ~`ro~ hexe bhe so~ ion g~alJ~ ~n~ ~h~ e~rapor~tor 31 ~hrough plpelin~ 32c ~rhe eva1pt)r~o~ 31 ~ heaked b;s~
~t~m ~hr-JI~.tr,h plpe-jo~ 33 ~d bhe cond~ate o~ the he~tlJlg s~sJm dep~r~s bhrough p~pe-jo~ 3~ ~h~ ~flam ev~poratsd ~rom the ~301lltion get~ to the ~o~.n~r 29 from the o~aporator 31 through a plp~l~e 35~ ther~ lt gebs ¢onden~od ~n~ the d:l~b~llabe i~ removed b;~ bhe pump 30, q!he ~s~m ~ h~ p~ 30 :~9 ~u~ h~ h~r the d i~ tilla be it i~ ~pable o~ :remo~ g ~ihe nen-c~ndensabl~
~ase~, too. :From the ~v~por~or 31 lbhe oondexl~ed9 ~tiYe ~olutio~ is pumped by a ;pump 36 ~hreugh a p:l~el:l~e ~
to the pipe~jo~nt ?6 through wh~ch i.b ge~s bac~ ~e ~he l~quid ve~sel 1~ 'rhi~ de~ic:~a~k ~olll~kio~ xe~ene~ o~ 1 al~o shown b~ ~.lr~u-.it diag~am on :Eig,. 7 Xor ~he ~alc~ o~
better unde.rst~dl lu~d.i~ 1.F,~ ~! b~ ¢~
a ~mplest po~si~31e ~ por~or~ whi~h ;L9es c~nlg th~
~rrl~ L~ ~olutlo.n to be re~sener~ted a; cool~ med:lu~n :EOI' ~ n~ing ~h~3 st~}m e~poxati~d :~rom tihe ~53l~'1tii'.~;'~3L
.l~ring ~h~ n~ lorl~, H~we~sr9 ~or~ 'IJ~
~t ~ or~ p.~ us~ i~s~ mul~0~ p{~ ;r~

8 or ~ ~r ~ mu~ h ~p~
e$8,~ple Ç3!~; show:n in ~l~s., 1 O~ 10 ~ atu~l~y ira pl~Ge OI ~h~ belk ~vrlv~;yor ~m~ o~h~r r~n~p~ ly b~ ~p~ d b~ p~ r..~ QI
t i~ k~n ~ r~u~ r~p~ e~

- 25 -3L131~

hor~zontall~ but also a~ko~. ~rhe ~ross-section o~ the liqu:Ld ue~e~ 13 i~ mu~h ~.;Lgger bhanL ~hat o.~ pipe-joints 26 ~n~ 279 ~ox bh~s xoa~o~ it ~ praetical ~or onsuxillg even ~bra~m:~g picbure to lo~ bhe desi~c~rlb solutioIl ~tre~m ~n and oug o~ ~h~ u~ ~e~l 13 ~ob only bhrough 3ing le i~omin~ ~nd ou~go~g P~ ~ but bhrough sf ono~ al-ong ~ha wiabh of the ve~el 13~ -. 5 and 6 ~ow a~obhor em~od~msxlt which woxkswith horizontally m.o~ing proauc~ 50 and ~ ~o:nta~s~ing ~evice 43 placed b~ e the product 50$, brin~ bout ver~ical l~guid film 41 o~ a de~cc~ 1$~1~
~ he produ~t 50" s~wn ~sood on the dr~w:~ngg i~ put onto CQrriag~ 51 with ~heel~ ~ppor~ed :~ be~ri~g~ on agle 52) and mo~e~ ~rery ~lo~l~ iorws.r~ on ba~ement 49 ~.
~he di:reG~ion o~ e~rrow 53~ ~bove bhe top o~ th3 prsdu.~b 50 the d~ing eompartment 40 is c 1o~3ea3 ~;y ~ 3e roo:~ 54 &
'~hs whole dry~g s.pp~rabu~ is clo~0d ~rom aboYe a ~hell~roo~ ~i5r which ~ha ~al~e roo~ 54 ~ co~te~
by ~u~pe~cllng colu~n~ 65~ he ~h~ f 6~ is ~lo~ed (~3.
two ~id~ by walls 37 and 38 re.sp~ v~ly g bhe ~
have ~ates 39 -ln them ~or bhe pr~oduG~ 50~D ~h~ alr ~r~am ¢lx~ula~ d~r~3.~n ~ ro~ ;eec~
o~ v~ ilato~ ~6 and 66~ dr~en b~ eleckr:Lo mol;or~ 46 ~nd 46' r~pe~t~ b~ ~to a ~par~hlo~ w~

h ~1 ~p~ 7 ~ $~a~s ~o ~h~ d~ g ~om3~.r~men~ 40 b~bw~en th~ ~sement 4 ~nd the :E~l~e roo~ 549 from bhere it g9~i~1 to li~uld ~llm~
41 of ~he con~aG~ing de~ 43, lthen ~hrough ~othar opening 47~ be~ erl the ~hell~ro~ 65 ~ld the fal~s roo~
54 back to the ven~ilator~ 66 and 66~D A3 in the embodimen~
~hown there are kwo vontllators 66 and 66~" two parallel partial air ~tream~ ~r~ going ~o ~ome s.bou~,.
Th~ contacting device 43 in thls embodiment~ a~
~hown in Fi~ ~" 5 and 6 ~on~ 5 of three ligu;Ld film modules 48~, 4~3 and 4~C plRced immediatel;y side b;y s~de.
Ea¢h module hE~s an individ~l l:lquid c:~rculation a~ all modula~ have a commo~ lower l~quid ou~L~ chann~l 62 through which they ~re conne~t~d to a regener~bor nob shown he~e ~ith pipe-joiIlt 67 and 68. ~he acbive ho~
de~iccant llqu~3 com~3 ~rom bhe re~,enerator ~nter~ thxo~h the pipe-joi~ 679 ~hen gebs more and more d~ubad b~y ~ircula~ion in 1~5Luid iilm modllle~ 4~ 4~3B ~ ~8C a~ .
it passes the ~nne:L 62 ~1 the dlrectlon oX s.rrow ~3 then ~hrou~;h ~he pipe-~oinb 68 $t ~ets in~o bhe ~ ger~e~ e~
~ ha re~ene:rator can b~ l;lke ~he O:llQ~3 $hoW~ ~
~gO 1 or ~ig~, 4 but multi--effecb a~apora~or~ ~ho~ ~Q
~igure~ 8 axld 9 ~rs al~o ~uitabls~ and ~o læ-~nulti~ 0 f lash evEIp~:~3tor o~ Fi~ O lO~
~ he l~uia film modules 48Ap 4~s ~;nd 4~c ar~
~imil~rly c~n~bru~ed~, ïor bhi~ rea~o~ we ~e~oribe the l~guid ~llm module 48~5~ onl;y~ ~ upp~ rea~pb~le pl~ ~9~ ~a~s~ r~f ~4 ~d ~ o~ d ~y ~ p~-.L~
Lo~k 56~ o the ~?ile lo~k 56~ a dow~ward.~ t3iI74~ ;edl ligui~ tribut;ing sur~a~e 57~ onne¢te~ Oil~ bhe : . .~ ' .

~7 --3~ 3 l.icluid ~ rlbu~ ing sur~ e 57~ there are ll~id ~llm oondu~ting ~lemen~ 58A9 e,.g~ ~ibre~ hown 1~ bhe dr~wing, goia~ down. ~lon bhe per~phe~ o~ ~a~h of ~he elements 58Q~ a :Liquid f ilm osme~ about,, ~11 bhe elemenb~
58~ belong:Lng to bhe llqu~d film module ~8~ tv~ether m~k~ up Q liqui~ lm group who~e.khax~terl~ic ~eQbure is tha~ ~11 the elemerlt~ bhe grollp ~o~dl2.0t a de~ sc~b liquid o~ bhe ~ama ~n~e~tr~1iion~ ~he e~ ment~ 58~ re~h down to the lower ~olle~ g cha~n~ 62 p:L~eed b~neabh3 ~ u¢ tion p~pe 59A æbartæ ~rom the bot $om o~ bh9 channel 6;2 thu~ ~onduc~s th~s de~ic¢~nt l~q~ to a 11~i~ rou3~Ln~
punnp 60~. The pump 6C)~ e~s~culate~3 the l~id throl~gh ~
~ube 61~ i~to the upp~r re~sept~c1e 55~7 from. bh~re ~hroll~h bhe pile locl~: ~6~ o bhe 11qu~ d~ribut~ng ~urf~ce 57~" ~nd then9 ~ he element~ 5~3~ in~o th~

q~he ~pper ~eoept~cle 55~ is ~e~arated :erem ~e uppe~ l~e~pb~cle e~ ~he neighbouri~g liguid ~ edul~
4~B~ but the oemmen lower ~haImel 6 ~l~es it po~
~h~t ~h~ q~ r~ c l~
~LA9 ~lB e,nd ~ give l~quid to one ~ne~}l~r ~eu~h i~
~6~.0~ W~ nn~ wh~h b010~
mg~du~e~ 48A7 4~;E3 and 48G9 re~pe~ti~ely a,re 9ep~ t~d ~ro~ er b~ ~epa elemer~ pr~
~a~ h~ ~iLgu~d ~b~0~ X~.u~;
d~ ~ o~ -row 63g b~ ~ho~ f~
b2,cl~ . Star~lng i~ tha d1reGtlon of ~.rrow 63 ~he ~u~ r~ lon~:ng ~ $h~

2~ ~
`~3~9~)3 f.ilm Tnodillc 48~ gebs l,he hot and ~cbl~e l~quid Prom the regeners.~or, ~his i~ c7~ lut~d by t~,he air ~br~am com~ng ~rom the dr;ying compartment 40~ so bh.e l~quid deliverea to ths ~ecolld liquid clrculQting circle balonging to ~hs l~quid film mo~ule 48:3 i~ the :~orlrl o~ ovelcîlow o~ the ~irst liqui d circul~ting circle i~ ~omesqh~k dilubed~ It i~ tha overflow of the l~æ~ ~ in the drawing the ~h~xd -li~uid circulQtlng circle whLch ~e~s ~a~k as dilub~d and cold desiccant 11 guid to tho xegenerator" ~aid liguid contai~ing all ~he moisturo whlch had boer. extr~e~e~
~rom the produ~t 50 by ~he ~ir ~x~amO
The two ~re~til~tors 66 a~ld 6~P bring ~bout 'GWO
p~r~llel partial a.ir stream~ he ~relocit;~ of each o~
~he partial air s~:ream~ ~hould be of ~ vallle, tha~ ~e liquid ~ilms along the ~onduct;~ng e~eme~ts 5~1~? 58~ ~d 58C ar~ xlot dis~tlrb~ he ~ir stream1 i~eO th.e ai~
stream~ doe~ Ilol; ~rxg o~f l~iquid p~r~ticle~ ~rom th~ m~
~eloci~ o~ 1 ~o 5 m/~e¢ is su~ t~ble~ The ~mi~odi~le~
~hown in F~ 3o 5 and ~ ~ ~imils,rly to tha~ ~nown ~n Fig~ o ~ ~ ~arrle9 out a ~ ounter~curr~Ilt d~i~g9 tho pl~odilct 5û movin~ 810wly in ~he t5irecti~l o~ a~
5~ ~ghll~ going through ~he dxyin~ compar~menti ~0 ~ee~
~ir stream~ whlch h~d boe~ ~o:nt~otied wi~ih mlore and ~19X'~
~cti~e de3i~cant;i liquidO A prere~:Ls:Lte o~ ~~.d goun~er -t:tlX'Xenl; d~in~; hare9 too is to have ~ t l.~ two }?art~1 a~r tre~m~. lti is e~p~lien~ to have G~10 p~r~i:lal a~
~biream helonging to each liquid filrrl ~]odi~le 4~3~.9 4~ an~
~8~ that i~ thfl nllmber of ~entil~tors .is ~qu~l ~o ~h~

.. ..
.

~ 2~ ~133L~3 th~ uld ;Ei ïm mociule~
~rhe con~tr~t~orl o~ tne d~1o~ li~id~
~1rculate~ ~ bhe l~guld ~ mo~ale~3 ~8~5~ 4~3 a~d 48G
¢~n be i~Gr~as~ in a ~eqlle~o~ ~if~erenk ~rom ~hab o~
bhe modul~ pacs. ~he ~ U~C0 ~an be arranged a~
~e~m~ be~ w~ th app~opri~e ~o~g o.~ dual ~ection~
o~ the ~hannel 62 belon~ bo ~ ll~idual moaul0~ ~or instance, ~rom the ~eGtio~ o~ t;h~ ~h~el 6~ bel~g$~
to llguid ilm mo~ule 48C bhe de~iG~n~ :!iquid call ge~
into the ~ecbion bel~ o li~uid ~ilm module 48~
in~e~d o~ ~he ene ~elo~ing bo liguid ~llm mod~le 4~B
through ~he 8ep~ 1em~.~t; ~6~, axl~ :erom ~here ~bo tha se~bioll be10.~i~ to 11~i~ film modu10 4823" I~ ,h a wa~ t~hs apparat~ a~cord~ o ~he inventlo.rl ¢~ b~
~rogrammed wlbh regar~ b~ the dr~i~g pre~Gripti~~ o~
the ~r~du~b 50 goi~g bhro~h the ~ com~rtm~n~ ~0, ~ bh~ d~m~n~ sh~n ~ o~
b~r~r~ th~ d~ ompaxkmerLt 4~ o~ th~ le~ h~d ormlrlg a ~ quid curtai~''tQ ~ ~ne l.~ id f~
~XQ~7~h~ bout ~ccQrd~ ta ~h~ ~ven~:Lo~ e~
dr s~ ~he a~ 43 l so b ight ~nd ~ of ~he d~ om;p3. r~,me~t 40 D more o~ n b~ c0d l~ ~h ~ ~a~ ~ha~ ~k ~ Ld~
co~p~m~ $~ ~o~ b~w~
~æ~ o~d $h~w~ . 5O ~.,o~
n~ h~ only ~h~ ort~ is t .he e sLr~m 0~ hrou~ ~h~ t~
~e~rcu~ioIl,, and ~he ~o.n~actin~ 3eViGe ~ nd th~ 5 - , ~

- ~o -~3~3 ~ompartment 40 ~re a~ranged and place~ i~ such a wa~y th~t the air stream su~er~ th~ lea~t possible alt~rakiorl o~
elocit;y ~nd directio~ YJh~n going ~rom on~ to the other.
It is ob~iou~ bh~t these conditions are ful~llled 1~ ~11 the embodiments mentio~led.
~ he t~pe of the contaoting devic~ 4~ ~hown i~
Fig. 5 is the same as that o~ the one shown in Fige 1 but it ~an al~o be made ~n a die~erent wayO Se~ral ~o~bacting d~rice~; ap plica~le i~ ~he apparatu~ according bo ~he ~ren~ion are d~3cr~bed ~ ~.S. Pat~nts ~o, 3,B57 and 4,009,æg, ln Eungarian P~tenb ~o. 168,4~1 and in Bri~ish Pat~nt ~o~ 1"36~5,523. In ~he apparatu~ accord~
to the inve~tioll ib i~ high~ advanbageou~ to apply aqlleous ~olut~on of ~al¢iu~ chloride ~n the concenbration oiS 40 to 50 % a~ a da~ic¢a~t liquid,. ~hs pollukion geb~
inbo the de~iccant ~olubion can be elir~ ted ~ith a ~a~ he ~ame ~g a~ ~he on~ de~¢r bed irl ~o~ne~t~o~
to the ~mbodlment~ ~hown 1~ Figs~ 2 to 40 ~ d 6 ~o do nLot show ~ r~generator ~
it Gan be th~ same a~ that ~n ar~ of Fig~,, 1, 4~ B~ 9 ~a 10. With ~h~ ~pproprtate ~election o:e r~genara~lo~ it 1~ ~lso po~3s~ble ~o en~ure for tha ~ct~:~e ~oluliio~ arr~
throu~h pipe ~o~nt 67 to ~e ~ hot a~ ~ ne~a ~d ~o ~h~ ~
it c~ he~.b th~ air ~tr~am and t:hrough it the prodllc~ 500 ~!ith the h~lp of liquid film mod~l~s ~8A~ 4~ and 48~
is posciibLe to ~et a te~p.~ra~ura progr~m ~or the produob 50 going ~hrough ~h~ dryirig co:npar~ment ~0,, - 31 - ~ ~ 3~L9~3 Fig~" 7~ 8~ 9 and 10 show varlou~ ~olutions ~or t~ regexlerator~, Havlng con~idered that ~he xage~ex~or come~ about ~rom di~ïerent connecting of deYioe~ per se know~ the variou~ l~egenerator~ ~o be appllsd ~n the ention ars shown in FigsO 7, 89 9 and 10 only wlth cir¢uit diagramsO For the sake o~ l~c~dibg we marked each -oper~tion with a separa~e s¢hemati~ slgn in lthe ci~cu~t diagram~ but the ~nv~nbion can be realizsa al~o ~ ~uch a way that9 for ~ns~a~ce, moro th~ one ~0Y~ce i8 pl~ced i~o ono cas ing ~
:Fig~ 7 repre~ent~ the circ~it d~gr~m c~ the regenera~or show~L in Fig~ 2 ~o 4 and des~ribe~ in rel~tlo~ -to these ~i~ure~ in d~ ilo Fig. 8 r~pres0n~ a ~egerler~itor which uses the ~eam ev~pors,t~d ïrom the ~esiGcant l~quid ~or m~ing to boil the liquid to be re~ener~e~9 and ~he s~e~m coming oî the dep~rt~a~g a~tYe liquid heag~3 the ~ncom~ ilu~d llauld. ~his reganerator i~ 2~ multi~ e~f2~t ~apo:rator"
!l~he ~luted lic~uid ~s pRmpe~l by ~ pump 70 iXltO a ~o~denser 71~ there 1~ se~v~s a~ coolirL~ medium ~or ~lhe eonde~s~x 71.~ ~heIl wh~l~ eool:lng the l~quid evapor~bin~
~rl heat e~l3h~nger~ 72 an~ w~ned ~u.rth~r, ~inall~ it get~ i.nto ~n ~7~.por~bor 75 ~h.rou~gh ~ p~pel~0 ~4~ ~nis e~apo~ator 75 i~ he~ted fr~m ~h~ out~id~ with h~ b~en i~ For inC~nce9 aocordin~, to the emho~lment .
shownJ 3~ea~ is t:~ken in throagh a pi?~-~olnt 7~ th~s g~ co~en~e~ arl~ ~he oondensate ~epart~ th~ough ~
p~elin~ 77~ 0~ ooux~e9 flu~ gas, r~3i~nt h~t;, ~olar energy or Romothlng else can also be u~ed fo:r hestiflr~, ~rom here through a heat exchangoL 7~ and ~ th:rottle 7~3 the liq~ gebs into a~ evaporator 79, whe:re it i~ th~r boiled b;y bhe ~team produced i~ the evaporator 75. ~I orn here a pump 83 pump~ ~he liguid through the hoa~ 3xci~n~;o:r 72 to a pipe-aoint 83 which i~ conneGted to ~ ~pe- jo~.nti conducting the active l:lquid i~ the dryer body it~
e.g" l;o the pipe-~oint 67 ~n Fig. 6. The sbeam produced he evapor~tor 79 khrough ~ p~peline 84 and t}l~
Gondensate of ~he steam heating the ev~por~tor 79 through a ~hrottle 81 gat in the conden~ 71 ~nd both heat thero ~he diluted, i~coming d esiccant li~uid . ~h~ condensad distilla~e and the non-conden3~ble gases are removed by pump 8~o Fig. 9 shows the circuit diagram o~ an embodiment o~ the regenerator which i~ Qlso a m~lti-effect evaporatQr and u~es the ~team evapor~ted ~rom the di1uted li~ui~
~or hea~ he incomin~ diluted liquia to be re~eneratsd.
The diluted liquid is pu~nped ~o a conden~er 91 by a pump 90 ~s Gooling medium, there ib warms llp) the~
coolin~ the departing alra~d;s~ ~o~den~3ed l:~qui~ h~
heat e~changer 92 ~b goeE~ on warmir~ and get~ into e~aporator ~3. P~rom hexe ~ ;EUZ~p 94 liake~ 1~ through h~t ex~hanger 95; wh~re eooli~g bhe ~c~ive 11~d it g~ ed ~ fur~her to a~ ev~porator g6~ re i ~
eYs~pc:~k~d with hea.k take~ in ~:rom out~ide, :eor e~ample wibh ~t~arn take~ 1~ through o. pipe ~olnt 970 ~he co.nden~at.e o~ ~he ~tea~ departs throu~h 8. pipe-aoint g8. ~I!he sbeam ~3~ 3 which had come about in the evaporator 96 boils the diluted liquid in the evaporator 93. The condensed, active liquid through a pipeline 99 gets into the heat exchanger 95, then into the heat exchanger 92, and departs through a pipe-joint 100 towards the dryer body e.g. to the pipe-joint 67 in Figure 6.
The steam produced in the evaporator 93 gets into the condenser 91 through a pipeline 101, condensate of the steam heating the evaporator 93 gets into the same place through a throttle 102, there it heats the diluted liquid, then the distillate produced by condensing and the gases not condensable are carried away by a pump 103.
Figure 10 shows the circuit diagram of a further embodiment of the regenerator in which the heat released during condensing the steam evaporated from the liquid by flash only warms the liquid to be regenerated but does not evaporate it.
This regenerator is a multi-stage flash evaporator.
The diluted liquid is driven through condensers 112, 113 and 114 by a pump 111. On leaving the condenser 114 the liquid goes through a throttle 115. The pump 111 and the throttle 115 are arranged in such a way that the pressure of the liquid when going through condensers 112, 113 and 114 is bigger than the saturation pressure all the way through, so vaporization does not occur anywhere. The temperature of the diluted liquid serving as cooling liquid in condensers 112, 113 and 114 is increasing. After . ~

' ~ ',, , '` ' ~ .

34 3L~3~9~3 the throttle 115 i;n an a~aporE~tor 116 steam i~ releasaa ~rom tha liquid wi~hout he0.t tran~fer. ~hi~ steAm ~et~
~onaen~sa in the cond~nser 113. The liguid 13OB~ O~ to an eva3?orator 117 where more steam is released ~rom it wh~h gets conden~ed in tha condon~er 112~ ~h~ condenso~ active liquid tha~ is le~ carried back to ~he drying bodg by a pump 118~ e~g. in ~ , 6 ko the pipe-~olnt 67t, ~he distillate ~onden~ed in the cond~er 11~ through ~ pipe-line 119 gets to ~he Gondsn~er 11;~9 ~Nhl3re iti fl~3he3~
~I!he di~tillat0 ~d the llon-oondensabl~ ga~e~ are pamp~d away by a pump 120.
I~ the cond~nser 114 the dil~ted liqllld to be reg0nerated ~ho~l~ be he~ed bg heat b~ke~ rom ou~
~ida5 for e~ample with s~Geam t~ke~ ~ bhrough a pipe-~o~b 1219 the condensabo o~ ~he steam deparkff bhrough ~ pipe-- jo~ n~ 122 .
Wibh re~p~¢t to t~e co~trol of eguipme~ts o~ bh0 re~;sners.~or i~ is e~pedie~t to alter the embodimerlt~
de~ e~ above ~ ~u¢h ~ w~y that onl~y e. parb o~ the dl~ uted de~iccant liquid ~eb~ Gonce~r~ted ~ he oth~r par~ i~ mi:~ad with the oo~¢~ l3partO Ib i~ thi~ ;re whi~h ~3 ~o b~ used as ~eb~e de~i~anl; li~d ~ the d ~i~ bod~
For the ~al~e of ~i~pler de~cripti~n 1~ t~ embod~
.~b~r0 we ~howea ~wo ~vapor~or~ :IJe~ tWC~ tag0ll O~ bllt;.' s~ ¢o~e it i~ po~ible and ~d~i~ab1e ln th~ ~nt~r~b o~
~ re~ing the en~rgeki~ e~icienoy bo ~p~lg more ~age~O

I~ Fi~. lO ~k i~ ~hown th~ ~ha:~ ~he ~1Q~ he~
produced by the regenera~or ~armot be l~ ill~eta 1;~ 'Gha drying bod~ or whe~ t~he he~t 109~ o:~ khe drying bedy i8 little (e.g,. ~ ~umme~ he ~e~Gcan~ r~genera'cln~
~skem ~hould be balanoea9 :k~ 10 t;her0 ar~ two e~pedient ~o~ions sppll~able ~epara~eIy bU~ ~lso bo~
~e~her. A~ tv the ~`lr~t ss~ tion ~he coIld0n~er 112 musb be pro~ided with coollng medlum ~xom the eu~d0 e.~5,.
coolin~ water and ~031~bl~ ~ub~idiarg surface e~,g~ co~l pipe. his l~tter can be place~ in a ~ep~rate Ga~
such a ca3e bhe ~beam ~?a~e~ mll~t be cor~e~ed wit.h pipe~
linas. aooling wabar c~ :~or e.xample enter bhe hea~
exch~ger ~hrough a pip~~jol~b 123 a~d ~eave i~ through 8. pipe-aolnt 1240 ~¢~x~ o ~he ~eGond ~oLution the dilubed lig.uid en~rl~; the Gon~en~er 11~ i~ pra-cooled in a hea~ e:~chal~er 127 w~i~h i3 1~OO~e~ a mediu~ e~c water entering t,hrou~h a p~pa~o~n~ 1~5 ~n~ ïe~ing through a p-ipa--joix3k 'æ6 m~ nt di~g ~0 ~7îg~,, 7~
those ~wo ~olu~ior.~ lI'e al~e applioab~eO In bhi~ r~pe~t ~n oquiv~l enb o~ th.a ~o~derl~er 112 Ceel13b ~l~iditiOna~
in -~ig. lQ i~ b7ne ~o~d~ ex ~ n Fig~ 7y ~h~ ~axlderlser 71 in ~ ,, 8 ~nd ~he oc?~ld,~er 91 i~ F Lg9 9~ ~h~ ~eak e~ r~ser l~?.r~7 ~hown ~.~ F:~g~ 3.0 musb be inser~ed b~
~h~ n~ 7~ d ~ pu~p~ j7C;i ~ g~ ' ~f ~ 7. ~ ~n~ iv~ s~S3 ~ r~ 8 ~v.n~

~3~ )3 r~o~ nge,s mi~ht be made ~ bhe embod~ma~
herei~ di~olo~ed wibhout ~ep~r~ rom the ~plri~ o~
~he inventiox~ der~tood tha~ aLl m~ber here~
~hown or ae~ be~ ~hould b~ de~m0d lllil~trQti~e R~1(9 llOt b~ w~ o~ limit~tio~3 ..

;

Claims (32)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of drying products comprising the steps of introducing the product to be dried into a drying compartment; continuously circulating a drying gas stream so as to cause it to pass past the product to be dried;
contacting the drying gas stream with a desiccant liquid to remove moisture from the gas; and regenerating the desiccant liquid by circulating at least a part of it through regenerating means to remove moisture therefrom, character-ized by producing at least one layer of the desiccant liquid at the boundary of or within the drying compartment, and traversing said at least one desiccant liquid layer by the drying gas stream.

2. The method according to claim 1, characterized by that said at least one desiccant liquid layer is a substantially horizontal liquid layer, and said drying gas stream is bubbled through said substantially horizontal liquid layer.

3. The method according to claim 1, characterized in that said at least one desiccant liquid layer is produced by causing the desiccant liquid to flow on liquid film conducting elements arranged in at least one plane at the boundary of or within the drying compartment, and, said contacting is performed by causing said drying gas stream to pass between said liquid film conducting elements.

4. A method of drying products comprising the steps of moving the product to be dried through a drying compartment; continuously circulating a drying gas stream so as to cause it to pass past the product to be dried; contacting the drying gas stream with a desiccant liquid to remove moisture from the gas; and regenerating the desiccant liquid by circulating at least a part of it through regenerating means to remove moisture therefrom, characterized by bringing about continuous heat exchange between the desiccant liquid and the product to be dried so that the heat is transmitted by the drying gas stream between the desiccant liquid and the product to be dried.

5. The method according to claim 4, characterized by that said heat exchange is performed by heating the desiccant liquid in the course of said regeneration so that the drying gas will be heated to a predetermined tempera-ture by contacting the desiccant liquid during said gas circulation.

6. The method according to claim 5, characterized by that said predeter-mined temperature of the drying gas is at least 40°C.

7. The method according to claim 4, characterized by that said desiccant liquid is a desiccant solution; said regenerating is performed by evaporating the desiccant solution; and the steam evaporated from the desiccant solution is at least partly condensed by the desiccant solution to be regenerated.

8. The method according to claim 7, characterized by that said evapora-tion is performed by a multi-effect evaporation; and the steam evaported during the first boiling of the desiccant solution is at least partly condensed by the incoming desiccant solution to be regenerated.

9. The method according to claim 7, characterized by that said evapora-tion is performed by a multi-effect evaporation; and the steam evaporated during the last boiling of the desiccant solution is at least partly condensed by the incoming desiccant solution to be regenerated.

10. The method according to claim 7, characterized by that said evapora-tion is performed by multi-stage flashing.

11. The method according to any of claims 8 to 10, characterized by further comprising the step of cooling the desiccant solution after said contacting and before said regenerating in dependence of the cooling of the desiccant solution during said contacting so that the incoming desiccant solution to be regenerated is of a predetermined temperature.

12. The method according to any of claims 4 to 6, characterized by further comprising the step of producing at least one layer of the desiccant liquid at the boundary of or within the drying compartment.

13. The method according to claim 1, characterized in that said continuous circulation of the drying gas stream is performed by conducting the drying gas stream in a path section being in the drying compartment between the product to be dried and the desiccant liquid so that in said path section the ratio of the maximum and minimum velocity of the drying gas stream is smaller than five to one and the change of direction of flow of the drying gas stream is less than 30 degrees.

14. The method according to claim 13, characterized in that said drying gas stream is conducted in the drying compartment between the product to be dried and the desiccant liquid substantially without any alteration of velocity and direction.

15. The method according to claim 7, characterized by that said desiccant solution is an aqueous solution of calcium chloride, and the drying gas is air.

16. The method according to claim 4, characterized by that said drying gas stream consists of at least two parallel partial gas streams, the product to be dried is moved across said partial gas streams; and each of said partial gas streams is contacted with a desiccant liquid of specific concentration and temperature.

17. The method according to claim 16, characterized by that each of said partial gas streams is contacted with a more concentrated desiccant liquid than the desiccant liquid contacting the previous partial gas stream with respect to the direction of movement of the product to be dried.

18. The method according to claim 16, characterized by further comprising the steps of producing at least two separated groups of desiccant liquid films of different concentration; placing said groups of desiccant liquid films side by side in the way of said partial gas streams so that each of said partial gas streams is contacted with its own at least one group of desiccant liquid films.

19. The method according to claim 18, characterized in that each of said groups of desiccant liquid films is provided with its own liquid circuit; the liquid circuit of the last group with respect to the direction of movement of the product to be dried is fed with the regenerated liquid coming from said regenerating means; the liquid circuit of each preceding group is fed with the overflow of the liquid circuit of the subsequent group; and the overflow of the liquid circuit of the first group is conducted into said regenerating means.

20. An apparatus for drying products comprising at least one drying compartment for the products to be dried; at least one contacting device for contacting a drying gas stream with a desiccant liquid to remove moisture from the gas; gas conducting means for conducting the drying gas stream in a sub-stantially closed path through said drying compartment and said at least one contacting device; gas circulating means to cause the drying gas stream to circulate along said closed path; regenerating means for removing moisture from the desiccant liquid; and liquid circulating means for circulating at least a part of the desiccant liquid through said regenerating means and said at least one contacting device, characterized in that said at least one contacting device includes means for producing at least one layer of the desiccant liquid to be contacted with the drying gas stream; said at least one contacting device being located at the boundary of or within said drying compartment and being disposed across said path conducting the drying gas stream.

21. The apparatus according to claim 20, characterized in that said at least one contacting device comprises a vessel for producing a substantially horizontal desiccant liquid layer, said vessel having on its wall bubbling caps for bubbling the drying gas stream through said liquid layer, said vessel being connected to said liquid circulating means so as to cause the desiccant liquid to flow along said vessel, and said drying compartment being located above or below said vessel.

22. The apparatus according to claim 21, characterized by that said drying compartment comprises a device for transporting the product to be dried through said drying compartment, said transporting device having openings for letting through the drying gas stream, but not letting the product to be dried drop.

23. The apparatus according to claim 22, characterized by that said transporting deivce is an endless belt conveyor, and said gas circulating means are ventilators placed side by side along said belt conveyor.

24. The apparatus according to claim 20, characterized in that said at least one contacting device comprises liquid film conducting elements disposed so that the drying gas stream is passing between them, said liquid film conduct-ing elements being arranged in at least one substantially vertical plane at the boundary of or within said drying compartment.

25. The apparatus according to claim 24, characterized in that said at least one contacting device further comprises a receptacle for receiving and holding the incoming desiccant liquid, at least one pile lock to guide in film form the liquid out of said receptacle, liquid distributing means having at least one distributing surface connected to said at least one pile lock and facing downwards, and liquid outlet means, wherein said liquid film conducting elements are connected between said liquid distributing surface and said liquid outlet means so that they conduct liquid films from said surface into said outlet means.

26. The apparatus according to claim 24, characterized by further comprising a basement, a shell-roof, and a false roof provided with openings for letting through the drying gas stream and located between said basement and shell-roof; said drying compartment being located between said basement and said false roof; said gas circulating means being placed between said false roof and said shell-roof; and said at least one contacting device being disposed at said drying compartment so that said at least one vertical plane formed by said liquid film conducting elements extends between said basement and said false roof.

27. The apparatus according to any of claims 24 to 26, characterized in that said at least one contacting device consists of at least two liquid film modules placed side by side, each liquid film module has its own liquid film conducting elements and own liquid circulating device producing a liquid flow circuit to form the liquid films on said own conducting elements, and said liquid film modules are provided with a common liquid channel interconnecting said liquid circulating devices, said common liquid channel being connected to said liquid circulating means, and said gas circulating means being adapted for circulating at least two parallel partial gas streams so that each of said partial gas streams is passing its own at least one liquid film module.

28. The apparatus according to claim 20, characterized in that the ratio of any two flow cross sections of said gas conducting means in said drying compartment between said product to be dried and said at least one contacting device is between 0.2 and 5; and said at least one contacting device is located at said drying compartment so that the drying gas stream is flowing between the product to be dried and said at least one contacting device with a directional change of less than 30 degrees.

29. The apparatus according to claim 28, characterized in that said flow cross section ratio is between 0.5 and 2, and said directional change is substantially zero degree.

30. The apparatus according to claim 28 or 29, characterized in that the distance in said drying compartment between said product to be dried and said at least one contacting device is less than the hydraulic diameter of said gas conducting means between them.

31. The apparatus according to any of claims 20, 21 and 24, characterized in that said regenerating means comprises a multi-effect evaporator.

32. The apparatus according to any of claims 20, 21 and 24, characterized in that said regenerating means comprises a multi-stage flash evaporator.